WASHINGTON — Never before in a presidential election cycle has there been so much discussion of the child tax credit — a tool many Democrats and Republicans have endorsed as a way to lift children and young families out of poverty. Just three years ago, child poverty rates fell significantly when President Joe Biden’s administration raised the child tax credit and made even the poorest families eligible. But the expansion only lasted a year. Congress declined to renew it.

There is hope for another increase in the tax credit, regardless of who wins Tuesday’s presidential election, but tension remains over who should qualify.

Democrats seek a massive — and costly — expansion of the social safety net. Vice President Kamala Harris has pitched a major increase to the child tax credit as part of her presidential campaign. Rather than providing the benefit through a tax refund, she wants to send monthly payments to parents, even those who aren’t working and pay no income tax. Republicans have expressed support for increasing the tax credit but also concern that for some parents, it could become an incentive not to work.

For all its economic prosperity, childhood poverty remains pervasive in the United States. Children under 5 are the age group most likely to encounter poverty and eviction, and more than one in six young people under 18 live below the federal poverty line.

Currently, the child tax credit gives families a $2,000 discount on their tax bill for every child under the age of 17 in their care. Families that pay less than $2,000 in income tax get a smaller benefit, and parents who are out of the workforce get none.

Harris has made expanding the tax credit central to her campaign’s messaging on the economy. Her running mate, Minnesota Gov. Tim Walz, has a resume that includes passing a state child tax credit.

Former President Donald Trump doubled the amount of the child tax credit during his administration. His presidential campaign declined to provide specifics on his plans for the child tax credit except to say he would weigh significantly increasing it.

The stakes of that debate are high for parents who are unable to work because of a disability, or because they are caring for children or elderly parents. Many have been excluded from the benefit because they are not earning income.